android - MonoDroid 进度对话框

Question

我想做的就是确保用户知道网络服务正在处理，这样他们就不会在它尝试工作时重复混合按钮。

        EditText partnumber = (EditText)FindViewById(Resource.Id.itemNumber);
        partnumber.FocusChange += (object sender, View.FocusChangeEventArgs e) =>
        {
            if (!e.HasFocus)
            {
                var pd = ProgressDialog.Show(this, "Processing", "Please Wait...", false);
                var res = new InventoryApp();
                res.partValidateCompleted += delegate { pd.Hide(); };
                var isValid = res.partValidate(partnumber.Text);
                if (isValid == "Not Found")
                {
                    partnumber.Text = "";
                    partnumber.RequestFocus();
                    partqty.ClearFocus();
                    AlertDialog.Builder builder = new AlertDialog.Builder(this);
                    builder.SetTitle("Invalid Part");
                    builder.SetMessage("Part number does not exist in database. Please ensure you are entering the correct part number and try again");
                    builder.SetPositiveButton("OK", delegate { });
                    var dialog = builder.Create();
                    dialog.Show();
                }
                else
                {
                    partdesc.Text = isValid;
                }
            }
        };

如果我将 pd.Hide() 留在代码中，那么我将永远看不到进度对话框。如果我把它拿出来，我只会在 web 服务返回它的结果后看到进度对话框，然后因为我没有把它隐藏在任何地方而保持不变。如何在应用等待 partValidate 时显示它以及何时可以隐藏它？

Answer 1

从您的代码来看，partValidate() 方法似乎是同步的。由于此代码是在 UI 线程上执行的，因此应用程序的 UI 将在该方法调用期间被阻塞，这可以解释为什么在它完成之前您看不到任何 UI 更新。您可以通过在后台线程上运行调用来解决此问题，然后在需要更新 UI 时返回 UI 线程:

partnumber.FocusChange += (object sender, View.FocusChangeEventArgs e) =>
{
    if (!e.HasFocus)
    {
        var pd = ProgressDialog.Show(this, "Processing", "Please Wait...", false);
        var res = new InventoryApp();
        res.partValidateCompleted += delegate { pd.Hide(); };

        ThreadPool.QueueUserWorkItem(state =>
        {
            var isValid = res.partValidate(partnumber.Text);

            RunOnUiThread(() =>
            {
                if (isValid == "Not Found")
                {
                    partnumber.Text = "";
                    partnumber.RequestFocus();
                    partqty.ClearFocus();
                    AlertDialog.Builder builder = new AlertDialog.Builder(this);
                    builder.SetTitle("Invalid Part");
                    builder.SetMessage("Part number does not exist in database. Please ensure you are entering the correct part number and try again");
                    builder.SetPositiveButton("OK", delegate { });
                    var dialog = builder.Create();
                    dialog.Show();
                }
                else
                {
                    partdesc.Text = isValid;
                }
            }
        }
    }
};

我有一篇博文 here解释了在 Android 应用程序的 Mono 上处理这种情况的各种方法。